1. Field of the Invention
The present invention relates to the implantation of prosthesis devices, and, more particularly, to the preparation of the femur for the implantation of a prosthetic hip replacement device therein by the formation of a centered bore in the intramedullary canal of the femur.
2. Related Art
Bone diseases and injuries to joints often make it necessary or desirable to replace a natural joint with an artificial prosthesis. One such replacement involves the fixation of a stem of a prosthetic hip joint within the femur. The femur contains an intramedullary canal filled with cancellous bone within which the stem of the prosthesis can be implanted. With such implantation, it is desirable to fix the stem to the femur centrally within the intramedullary canal.
In preparing the femur to accept the prosthetic device, the femoral head is removed to expose the intramedullary canal. A bore is formed in the canal and the femoral stem of the prosthesis is inserted into the canal and fixed to the femur by an interference fit, or by cement fixation.
When the prosthesis is joined with the femur, it is ideally centered within the intramedullary canal so that there is no undue pressure on the cortical bone which might cause pain to the recipient of the prosthesis and even result in bone penetration. The centering of the femoral stem of a prosthesis has been addressed. For example, Techmedia, a company located in Camarillo, Calif., has proposed using a small plastic centering device attached to the tip of the femoral stem. However, the attachment of such a device to a femoral stem creates several associated problems. For example, such plastic attachments increase the overall cost of the prosthesis. Additionally, the attachment of a plastic centering device to a metal femoral stem often causes some weakening of the stem, thus increasing the chance of deterioration of the fixation of the prosthesis to the femur and the likelihood that the prosthesis will need replacement. High intramedullary pressure may cause septemic fat embolism, i.e., cardiac arrhythmia, death.